Never send cold email from your main domain
Mailbox providers judge reputation largely by sending domain. If cold outreach from your main domain draws complaints or bounces, the damage lands on the domain your invoices, proposals and client email come from.
The standard practice is to send from separate domains that look like yours — close variations of your brand name — with their own inboxes, redirecting to your main site. If one gets flagged, you retire it; your main domain was never involved.
Authenticate everything: SPF, DKIM and DMARC
Authentication tells receiving servers that you're allowed to send as your domain. Without it, a lot of mail is filtered before anyone reads it.
- SPF lists the servers permitted to send email for your domain.
- DKIM signs each message so the receiver can check it wasn't altered and really came from your domain.
- DMARC tells receivers what to do when SPF or DKIM fails, and sends you reports about it.
Google's and Yahoo's sender requirements, in force since February 2024, expect every sender to authenticate, and ask bulk senders to use all three records, offer easy unsubscribes and keep reported spam below 0.3%. Cold outreach shouldn't be bulk mail, but those thresholds show what mailbox providers are watching.
Warm up new domains and inboxes
A brand-new domain that suddenly sends hundreds of emails looks exactly like a spammer. New inboxes need a gradual ramp — low volume at first, rising over a few weeks, with real engagement along the way — before they carry a campaign.
This is why honest outbound providers quote a setup period before anything goes out. Rushing it doesn't produce earlier meetings; it produces domains that are filtered for good.
Keep volume modest and spread it out
Each inbox should send a modest number of emails a day. When you need more volume, add inboxes and domains rather than pushing one inbox harder. Spreading sends across the day, and keeping them to working hours, looks like a person rather than a machine.
Clean lists: verify before you send
Bounces are one of the fastest ways to damage a sending domain. Verify every address before it enters a sequence, be careful with catch-all domains that accept everything, and never send to a list you bought and didn't check.
A smaller, well-researched list beats a large one on every measure — including deliverability, because relevant email gets fewer complaints.
Write like a person
- Plain text, short, one clear ask.
- No attachments and no images in a first email, and as few links as possible.
- Consider switching off open tracking — tracking pixels add a link-like element to every email and the data is unreliable anyway.
- Write for the recipient. Relevant email draws replies; irrelevant email draws spam reports.
Handle replies and opt-outs properly
Make it easy to say no, and honour it immediately and permanently. Someone who asks not to be contacted and gets another email is the complaint that hurts you most — with the mailbox provider and with the prospect.
Monitor, and act early
- Watch bounce and spam-complaint rates per domain and per inbox.
- Use Google Postmaster Tools to see how Gmail rates your sending domains.
- Check blocklists, and run placement tests to see where mail actually lands.
- Keep spare, warmed domains ready so a problem is a swap, not a restart.
This is the part of done-for-you cold email that clients never see and that decides whether any of the rest works. It's also why the monthly tech fee exists: domains, inboxes and sending software cost money whether or not a meeting books.